Air operated double diaphragm pumps are known for pumping a wide variety of substances. In some applications, double diaphragm pumps are utilized to pump caustic chemicals, in other applications, comestible substances such as flowable foods and beverages can be pumped. In such applications, the pumps are often constructed primarily of materials that resist corrosion and that are chemically compatibable with the substances being pumped. In this regard, polymeric materials are often used for various pump components.
To operate the double diaphragm pump, air motors are having flow control spool valves are often provided to regulate the flow of compressed air through the pump and oscillatingly drive the pump diaphragms. The spool valves generally include a valve housing that defines a valve chamber, and a spool that is received by the valve chamber. The spool includes a plurality of seals that delimit the chamber into two or more subchambers. The spool is slidably movable within the valve chamber such that the seals, and therefore the subchambers, move within the chamber to regulate the flow of pressurized air to the pump diaphragms.